Establishing structure/property relationships in atomically dispersed Co–Fe dual site M–Nx catalysts on microporous carbon for the oxygen reduction reaction

Abstract

Coupled metal–nitrogen–carbon (M–N_x–C) materials show great promise as platinum-group-metal (PGM) free catalysts for the oxygen reduction reaction (ORR). Herein, we report a facile strategy to construct atomically dispersed Co–Fe dual sites enriched on the surface of nitrogen doped microporous carbon (NC) as an efficient electrocatalyst for ORR. Synchrotron X-ray techniques indicate that the Co and Fe atoms are strongly correlated while further revealing that the longer-range lattice structure of NC is highly tunable. Density functional theory calculations reveal that the Co–Fe dimers are incorporated in the slightly disordered NC substrate, providing a lower adsorption free energy for O₂. The as-prepared CoFe–NC catalyst exhibited excellent ORR activities, while a CoFe–NC based zinc–air battery exhibited a power density of 115 mW cm⁻² and a specific capacity of 791 mA h g⁻¹. This work showcases a straightforward methodology for creating atomically dispersed catalysts and illustrates the importance of understanding how dual metal sites impact electrocatalytic activity.